 Between 1991 and 1993, Tang was seconded to the London Metropolitan Police under the Superintendent Exchange Scheme and performed the role of a Divisional Superintendent.Tang then became Assistant Commissioner of Police (ACP) in 1999, Senior Assistant Commissioner of Police in March 2002, Deputy Commissioner of Police in December 2003, and as Deputy Commissioner of Police (Operations) took over responsibility for all aspects of the operational policing of the Force.On 16 January 2007, he succeeded Lee Ming-Kwai as the Commissioner of Police.